C/2023 A3 (Tsuchinshan-ATLAS)
Comet· orbits the Sun
C/2023 A3 (Tsuchinshan-ATLAS) was the great comet of October 2024, a naked-eye visitor from the distant Oort cloud. It is on a near-parabolic orbit — effectively a one-time visitor that will not return on any human timescale.
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Key facts
Perihelion
0.391 AU
Eccentricity
1
Science
Physical
- Nucleus
- A few km across (estimated)
- Composition
- A pristine nucleus of ices, dust and organics, thought to be a first-time visitor from the Oort cloud. No spacecraft has visited — its size and composition are estimated from ground-based observations.
Orbital
- Perihelion
- 0.391 AU
- Eccentricity
- 1 · near-parabolic
- Inclination
- 139.11 °
- Orbit
- Near-parabolic — effectively non-periodic · a long-period visitor from the outer Solar System; no finite period is quoted
Activity
- Status
- Currently inactive (q = 0.391 AU, last perihelion September 2024)
- Becomes active within
- 5 AU of the Sun
Radiation & temperature
- Insolation
- 0.000653 S⊕ · 1/1,532 of the sunlight Earth receives
Discovery & history
- Discovered
- January 9, 2023
- By
- Purple Mountain (Tsuchinshan) Observatory and the ATLAS survey
- Method
- Photographic plates
- Name
- Named jointly for the Tsuchinshan (Purple Mountain) Observatory in China and the ATLAS survey.
C/2023 A3 was reported by the ATLAS survey in South Africa in early 2023 and then linked to earlier images from the Tsuchinshan (Purple Mountain) Observatory in China, so it carries both names. A near-parabolic visitor from the Oort cloud, it became the great comet of October 2024, putting on a spectacular naked-eye show before receding on its long journey outward.
Images
Images from open archives · credit shown per image